JP3872028B2 - Signal transmission system and signal transmission method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile communication radio system using an optical line, and more particularly to an improvement of an equalizer mounted between a receiving stage (O / E) of an optical module and a serial-parallel converter that performs serial-parallel conversion.
[0002]
[Prior art]
An example of a mobile communication radio system apparatus using an optical line will be described with reference to FIG.
[0003]
In recent years, in optical communication, high transmission capacity such as 10 Gbits Ethernet (registered trademark) has progressed, and deterioration of electrical characteristics of a high-speed differential serial line has become a problem. As a countermeasure, an optical module 7a and a serial-parallel converter 10a The error rate is prevented from increasing by inserting the equalizer 8 in between and correcting the waveform. Currently, the use of an adaptive equalization filter and a high-pass filter can be considered as a waveform correction method using the equalizer 8.
[0004]
As prior art documents related to the present invention, there are the following.
[0005]
[Patent Document 1]
JP 2000-022608 A [Patent Document 2]
JP 2000-151516 A [Patent Document 3]
Japanese Patent Laid-Open No. 04-274622 [0006]
[Problems to be solved by the invention]
However, the adaptive equalization filter has a fairly good correction of the input waveform, but the circuit scale is large and the cost is high, and the training area requires several bytes until the waveform stabilizes, so the delay amount is large. there is a possibility.
[0007]
In addition, since the cut-off frequency is fixed in the high-pass filter, when considering multi-vendor optical modules, the electrical characteristics are different from each other. Therefore, the waveform cannot be corrected with the optimum filter value, leading to an increase in the error rate. . Therefore, a method for reducing the error rate by using an inexpensive filter with a small delay amount is required.
[0008]
Accordingly, an object of the present invention is to provide a mobile communication radio system apparatus using an optical line capable of recovering data that normally causes an error as much as possible and realizing a reduction in error rate.
[0009]
[Means for Solving the Problems]
The signal transmission system according to the present invention includes an equalizer that corrects a waveform of a transmission signal, an error detection unit that detects an error of the transmission signal that has been waveform-corrected by the equalizer, and an error detection unit that detects the error of the transmission signal when the error is detected. Means for prohibiting output to a subsequent stage, and when the error is detected, causes the transmission source of the transmission signal to stop transmission of the transmission signal, changes the parameter of the equalizer, and And means for repeating the operation of transmitting a transmission signal until the error is no longer detected, and means for resuming output of the transmission signal to the subsequent stage when the error is no longer detected.
[0010]
The signal transmission method of the present invention includes an error detection step of detecting an error in the transmission signal whose waveform is corrected by the equalizer, and a step of prohibiting output of the transmission signal to a subsequent stage when the error is detected. When the error is detected, the transmission signal transmission source is stopped from transmitting the transmission signal, the equalizer parameter is changed, and the transmission source is transmitted to the transmission source. And the step of repeating until the error is not detected, and the step of restarting the output of the transmission signal to the subsequent stage when the error is not detected.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A comprehensive configuration of the signal transmission system and signal transmission method of the present invention will be described with reference to FIG.
[0012]
Referring to FIG. 1, a radio base station 1 that transmits / receives data to / from a higher-level device (not shown), a transceiver 2 that transmits / receives data to / from a mobile phone, and an optical fiber 3 that relays between them are provided. .
[0013]
The uplink includes a radio unit 4 that performs processing such as D / A conversion, despreading, and RAKE combining on the data received from the antenna 20 of the transceiver 2 and demultiplexing and parallel-serial conversion on the data from the radio unit 4. A signal processing unit 5 that performs (8B / 10B conversion) or the like is provided. Further, an optical module 6a (E / O unit) that converts the serialized data form from electricity to light, and an optical module 7a (O / O) that converts the light form data from the optical fiber 3 into electrical form data. / E section) and an equalizer 8 for optimizing the waveform of data in the form of electricity. Furthermore, a controller 9 for setting a filter parameter value of the equalizer 8, a serial / parallel converter 10a for converting serial data from the equalizer 8 into parallel data, and a baseband signal processing unit 11 for performing data processing such as 10B / 8B conversion are provided. Prepare.
[0014]
In the downlink, a parallel-serial converter 10b that converts parallel data from the baseband signal processing unit 11 that performs data processing such as 8B / 10B conversion into serial data, and a serial data form from the parallel-serial converter 10b are electrically connected. An optical module 7b (E / O unit) for converting light into light is provided. Furthermore, an optical module 6a (O / E unit) that converts data in the form of light from the optical fiber 3 into data in the form of electricity, and a signal processing unit that performs serial-parallel conversion, data demultiplexing, 10B / 8B conversion, and the like 5 and a wireless unit 4 that performs modulation spreading, A / D conversion, amplification, and the like.
[0015]
The 8B / 10B conversion is conversion from an 8-bit pattern to a 10-bit pattern for reducing the direct current component, and the reverse of the 10B / 8B conversion.
[0016]
A detailed configuration for dealing with an error occurrence according to the present invention will be described with reference to FIG.
[0017]
The filter parameter value of the equalizer 8 is switched by detecting the 8B / 10B error detector 51 that sets the flag ER_DET52 and the ER_DET52 when an error is detected from the output signal from the serial / parallel converter 10a. The PAL control unit 53 and the setting register 54 for setting filter parameters are performed in cooperation.
[0018]
The 8B / 10B error detection means that an error has occurred when an impossible 10-bit pattern is detected.
[0019]
In the data retransmission, the CONT_DATOFF control unit 55 that issues a data output stop command when an error occurs, the DATOFF function unit 56 that stops the data output from the baseband signal processing unit 11, and the signal processing unit 5 to stop and retransmit the data. The requested data transfer stop / retransmission request control unit 57, a data transfer stop / retransmission command control unit 58 that receives the stop retransmission request and gives a command, and a RAM unit 59 that stores data.
[0020]
Next, an operation for performing waveform correction according to the present embodiment will be described with reference to the configuration diagram of FIG. 2, the flowchart of FIG. 3, and the timing chart of FIG.
[0021]
First, when the power of the mobile communication wireless system apparatus is turned on (step 101) or reset, the controller 9 reads the type, vendor, and other types from the memory mounted in the optical module 6 (step 102). Each filter parameter value corresponding to the electrical output characteristics of the optical module 6 is initially set in the setting register 54 of the equalizer 8 (step 103).
[0022]
If no 8B / 10B error occurs in the 8B / 10B error detector 51 (step 105) after the start of transmission / reception operation of the mobile communication radio system apparatus (step 104), the normal mode is set (step 106).
[0023]
When an 8B / 10B error occurs (step 105), as shown in the timing chart of FIG. 4, first, after the controller 9 detects ER_DET 52, data output is stopped from the CONT_DATOFF control unit 55 to the DATOFF function unit 56 (step 107). At the same time, the controller 9 sends a data transfer stop request to the data transfer stop / retransmission request control unit 57 (step 108). The stop request data is inserted into the free area of the downlink user data and is received by the data transfer stop / retransmission command control unit 58 through the optical fiber 3. The RAM unit 59 receives the data stop request, RG (read gate) is negated, and data output is stopped.
[0024]
Next, the PAL control unit 53 that has detected the ER_DET 52 instructs the setting register 54 of the equalizer 8 to change the filter parameter value K (i) (step 109). After writing, a data retransmission request is sent to the data transfer stop / retransmission request control unit 57 in the same sequence as the above-described data stop request (step 110), and the data of the retransmission request is controlled by the data processing stop / retransmission command control of the signal processing unit 5. Received by the unit 58. The RAM unit 59 receives the data retransmission request, RG (read gate) is asserted, and data retransmission is started (step 111).
[0025]
When the limit number of data retransmissions is n and the number of prepared filter parameter values is i, if no 8B / 10B error occurs during n <i (step 105), the normal mode is entered and the DATOFF function unit 56 The output of data from is resumed (step 106). When an 8B / 10B error occurs (step 105), the filter parameter value is changed and rewriting is performed, so that data output is stopped (step 107, 8B / 10B error 105 occurs even when n = i) If so (step 105), the data retransmission interruption 112 is performed (step 112), and an alarm is raised to the upper level.
[0026]
(Other embodiments)
Another embodiment of the signal transmission system and signal transmission method of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram showing an overall configuration using a daisy chain. The transceiver 2a and the transceiver 2b are connected in a daisy chain to the radio base station 1 through the optical fiber 3, and the waveform correction is performed by the equalizers 201 and 203 at the reception stage of the transceivers 2a and 2b.
[0027]
FIG. 6 is a detailed block diagram. In the above-described embodiment, the waveform correction is performed by the equalizer 8 at the reception stage of the radio base station 1, but in this other embodiment, the block for performing the waveform correction is an optical module (O / E) Equalizer A (201) that processes the electrical output from 6b, and Equalizer B (203) that processes the received signal obtained by photoelectrically converting the upstream signal from the transceiver 2b by the optical module (O / E) unit 202b ). When an 8B / 10B error occurs in the 8B / 10B error detector A (204) and the 8B / 10B error detector B (205), the controller 206 detects ER_DAT207 or ER_DAT208, and the equalizer A201 or the equalizer B203 The filter parameter value is rewritten, and the system is operated using a retransmission retry sequence as in the previous embodiment.
[0028]
【The invention's effect】
The first effect is that the configuration of the waveform correction circuit of the smallest scale has a small transmission delay amount, and can realize a reduction in cost and a reduction in error rate. The reason is that an inexpensive filter is used instead of an adaptive equalization filter having a large circuit scale for the equalizer. At the same time, the fact that the electrical output characteristics (eye pattern characteristics) of the optical module have characteristics unique to each product name and each vendor is used to set an optimum filter value adapted to the characteristics.
[0029]
A second effect is that the error rate can be further reduced by applying the retransmission retry method. The reason is that the optimum filter is selected by retransmission retry from among the initial filter parameter values that are assumed to be optimum and several filter values that are assumed to some extent due to noise and impedance matching. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a comprehensive configuration of a mobile communication radio system apparatus using an optical line according to the present invention.
FIG. 2 is a block diagram showing an embodiment of a mobile radio system apparatus of the present invention.
FIG. 3 is a flowchart showing a retransmission retry method in the mobile communication system apparatus of FIG. 2;
4 is a timing chart of a retransmission retry method in the mobile communication system apparatus of FIG.
FIG. 5 is a block diagram showing an overall configuration of another embodiment of the mobile radio system apparatus of the present invention.
FIG. 6 is a block diagram showing another embodiment of the mobile radio system apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Radio base station 2 Transmitter / receiver 3 Optical fiber 4 Radio | wireless part 5 Signal processing part 6a, 6b Optical module 7a, 7b Optical module 8 Equalizer 9 Controller 10 Series parallel / parallel converter 10a Series / parallel converter 10b Parallel serial converter 11 Baseband signal processor 51 8B / 10B error detector 52 ER_DET
53 PAL Control Unit 54 Setting Register 55 CONT_DATOFF Control Unit 56 DATOFF Function Unit 57 Data Transfer Stop / Retransmission Request Control Unit 58 Data Transfer Stop / Retransmission Command Control Unit 59 RAM Unit 201 Equalizer A
202a, 202b Optical module 203 Equalizer B
204 8B / 10B error detector 205 8B / 10B error detector B
206 Controller 207 ER_DAT_A
208 ER_DAT_B

Claims (6)

An equalizer that corrects the waveform of the transmission signal;
Error detection means for detecting an error in the transmission signal whose waveform is corrected by the equalizer;
Means for inhibiting output of the transmission signal to a subsequent stage when the error is detected;
When the error is detected, an operation of causing the transmission source of the transmission signal to stop transmission of the transmission signal, changing an equalizer parameter, and transmitting the transmission signal to the transmission source is performed by the error. Means to repeat until no longer detected,
Means for restarting output of the transmission signal to a subsequent stage when the error is no longer detected;
A signal transmission system comprising: The signal transmission system according to claim 1,
The signal transmission system characterized in that the error detection means performs 8B / 10B error detection. The signal transmission system according to claim 1,
A signal transmission system further comprising means for setting initial parameters corresponding to characteristics of transmission line components in the equalizer at the start of operation. In a signal transmission method using an equalizer that performs waveform correction of a transmission signal,
An error detection step of detecting an error in the transmission signal whose waveform is corrected by the equalizer;
Prohibiting output of the transmission signal to a subsequent stage when the error is detected;
When the error is detected, an operation of causing the transmission source of the transmission signal to stop transmission of the transmission signal, changing an equalizer parameter, and transmitting the transmission signal to the transmission source is performed by the error. Repeating until it is no longer detected,
Resuming output of the transmission signal to a subsequent stage when the error is no longer detected;
A signal transmission method comprising: The signal transmission method according to claim 4, wherein
In the error detection step, 8B / 10B error detection is performed. The signal transmission method according to claim 4, wherein
A signal transmission method, further comprising a step of setting an initial parameter corresponding to a characteristic of a transmission line component in the equalizer at the start of operation.

Images